Disk drive storage devices typically include one or more data storage disks that are used to store information allowing a installer to read and write information from the disks. A disk pack refers to a plurality of data storage disks incorporated within a disk drive. The disks are stacked over one another and separated as by spacers. The disk pack is mounted over a hub assembly. A clamp secures the disk pack to the hub assembly. The disk pack is driven by a spindle motor which rotates the disks as a unit.
Various types of disk clamps can be used to secure the disk pack. One general type of clamp are those which utilize fasteners such as screws to secure the clamp to the hub. Another general type of clamp is one which does not use fasteners, and rather utilizes a retaining ring that is wedged between the central bore of the disk clamp and an annular undercut or groove formed on the outer surface of the hub.
Most manufacturing processes utilize manual installation of a disk clamp over a hub. It is possible to install the clamp through an automated assembly step (for example, by use of robotic assembly); however, because of the relatively small difference in the outer diameter of the hub versus the central bore in the clamp, the cost to incorporate the automated assembly step by use of precision robotics can be prohibitive; it is still more cost effective in most instances to simply use manual installation.
When installing the disk clamp, there are important considerations to account for that may ultimately affect the performance of the disk drive. One consideration is to reduce the amount of scraping contact that occurs between metal components thereby minimizing production of particulates which contribute to disk drive contamination. Another consideration is to provide installation of the disk clamp so that the disk clamp is precisely centered over the disk pack thereby minimizing overall imbalance of the disk pack. If a disk clamp is properly centered over the disk pack, then undesirable disk deflection, commonly referred to as “disk coning”, can be reduced thereby improving drive performance. If a clamp is not centered over the disk pack, then the disk clamp when secured will generate uneven forces across the disks thereby contributing to disk coning.
Regardless of the particular manufacturing process, it is desirable to provide a disk clamp having a construction conducive to being more easily centered over the disk pack. One obvious solution might be to simply reduce the gap between the outer diameter of the hub and the inner diameter of the clamp. However, an adequately sized gap must still exist between the inner diameter of the clamp and the outer diameter of the hub so that binding between the clamp and the hub does not occur when installing the clamp. Binding between the clamp and the hub causes production of particulates and therefore can create disk drive contamination. While a more centered disk clamp may provide better disk pack balancing and less disk deflection, centering of the disk clamp over the hub should not be achieved at the cost of creating contamination by increased scraping contact between the clamp and the hub.
Therefore, there is a general need to improve disk pack balancing and to limit disk deflection. There is also a need for providing a disk clamp that has integral centering features, yet does not compromise drive performance by introducing undue contamination during clamp installation. There is yet a further need to provide the centering features with different types of disk clamp constructions to accommodate various disk drive configurations. For example, a multiple disk configuration within a disk pack may correspond to a disk drive which is not particularly constrained with respect to overall height of the drive, commonly referred to as the “z-height”. On the other hand, some disk drives have a very constrained z-height, and accordingly, disk clamps used in these drives have a flatter shape to accommodate the z-height constraint.